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.\"	$OpenBSD: atoi.3,v 1.11 2013/07/17 05:42:11 schwarze Exp $
.\"
.Dd $Mdocdate: July 17 2013 $
.Dt ATOI 3
.Os
.Sh NAME
.Nm atoi
.Nd convert
.Tn ASCII
string to integer
.Sh SYNOPSIS
.In stdlib.h
.Ft int
.Fn atoi "const char *nptr"
.Sh DESCRIPTION
The
.Fn atoi
function converts the initial portion of the string pointed to by
.Fa nptr
to
.Li integer
representation.
.Pp
It is equivalent to:
.Bd -literal -offset indent
(int)strtol(nptr, (char **)NULL, 10);
.Ed
.Sh SEE ALSO
.Xr atof 3 ,
.Xr atol 3 ,
.Xr strtod 3 ,
.Xr strtol 3 ,
.Xr strtonum 3 ,
.Xr strtoul 3
.Sh STANDARDS
The
.Fn atoi
function conforms to
.St -ansiC .
.Sh HISTORY
An
.Fn atoi
function first appeared in
.At v1 .
.Sh CAVEATS
.Nm
does no overflow checking, handles unsigned numbers poorly,
and handles strings containing trailing extra characters
(like
.Dq "123abc" )
poorly.
Careful use of
.Xr strtol 3
and
.Xr strtoul 3
can alleviate these problems,
but
.Xr strtonum 3
can be used to convert numbers from strings much more safely
and easily.
